Convective Heat Transfer And Stress Analysis Of Supercritical Water Cooled Fusion Reactor Blanket

Nowadays energy issue is one of the most serious issues. The mostly used chemical energy is not recommended for long-term use due to its low caloric value and pollution potential to the environment. Nuclear energy is a vital member of new energy family, including fission and fusion. Fission energy comes from the fission of heavy metal atoms releasing enormous energy. Nuclear fission has been currently achieved commercial operation. Fusion energy is not yet commercially utilized. The fuel for fusion reaction is almost inexhaustible in nature, and its reaction products are less radioactive. Therefore, fusion energy is considered to be clean, safe and renewable.In fusion reactor, blanket is the key component for energy transformation. It enwraps components in plasma reactor and made up by the first wall and breeder zone. The primary functions of fusion reactor blanket are as follows: producing and transporting tritium; transferring neutron energy into heat energy and removing heat by coolant flowing through the cooling channel. The first wall has to withstand the heat flux from high-temperature plasma and also partially achieve shielding effect. Supercritical water (SCW) cooled blanket is one kind of blanket design proposals. It is cooled by supercritical water at pressure of 25MPa.This paper investigates the thermo-structural performance of the first wall and convective heat transfer in breeder zone cooling channel of SCW cooled blanket. In this study, a coupled code ANSYS CFX /ANSYS Workbench is used to analysis the temperature and stress distribution of structural material by one-way coupling approach. Firstly the temperature and stress in the first wall structural material of the existing SCW cooled blanket design is simulated to verify the fluid-structure interaction analysis method. Then different turbulence models are used in numerical simulation to find out their influence on temperature and stress distribution in the first wall. Different cooling schemes and different geometrical configurations of flow channel of the first wall are taken into consideration. Based on the results achieved so far, an optimized design solution is suggested on the modification of the design structure and geometric configuration of flow channels, which can effectively reduced the maximum temperature and stress of the structural material.Furthermore, convective heat transfer in the cooling channel of breeder zone is investigated by CFX simulation. Numerical results show heat transfer reduction near the pseudo-critical temperature due to the dramatic change of physical properties of SCW. The results also indicate that larger coolant flow rate leads to improved heat transfer, which becomes more apparent along the flow pass. At the same time, the influence of buoyancy force on the heat transfer reduction at mixed convection conditions is studied. Simulation results show that phenomenon of"heat strengthened" and "heat weakened" occur alternatively according to the changes of flow rate and flow direction (along or again buoyancy direction).